Spitzer observations of hydrogen deuteride

Abstract

We report the detection of interstellar hydrogen deuteride (HD) toward the supernova remnant IC443, and the tentative detection of HD toward the Herbig Haro objects HH54 and HH7 and the star forming region GGD37 (Cepheus A West). Our detections are based upon spectral line mapping observations of the R(3) and R(4) rotational lines of HD, at rest wavelengths of 28.502 and 23.034 micron respectively, obtained using the Infrared Spectrograph onboard the Spitzer Space Telescope. The HD R(4)/R(3) line intensity ratio promises to be a valuable probe of the gas pressure in regions where it can be observed. The derived HD/H2 abundance ratios are 1.19(+0.35/-0.24)E-5, 1.80(+0.54/-0.32)E-5, and 1.41(+0.46/-0.33)E-5 respectively (68.3% confidence limits, based upon statistical errors alone) for IC443 (clump C), HH54, and HH7. If HD is the only significant reservoir of gas-phase deuterium in these sources, the inferred HD/H2 ratios are all consistent with a gas-phase elemental abundance [n(D)/n(H)](gas) ~ 7.5E-6, a factor 2 - 3 below the values obtained previously from observations of atomic deuterium in the local bubble and the Galactic halo. However, similarly low gas-phase deuterium abundances have been inferred previously for molecular gas clouds in the Orion region, and in atomic clouds along sight-lines within the Galactic disk to stars more distant than 500 pc from the Sun.

12 pages, including 5 figures. Accepted for publication in ApJ Letters

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Cited by in corpus (16)

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• Spitzer observations of HH54 and HH7-11: mapping the H2 ortho-to-para ratio in shocked molecular gas
• Spitzer spectral line mapping of supernova remnants: I. Basic data and principal component analysis
• A spectral line survey of Orion KL in the bands 486-492 and 541-577 GHz with the Odin satellite II. Data analysis
• Mapping warm molecular hydrogen with Spitzer's Infrared Array Camera (IRAC)
• Water around IRAS15398-3359 observed with ALMA
• New Phases and Dissociation-Recombination of Hydrogen Deuteride to 3.4 Megabar
• A HST study of the environment of the Herbig Ae/Be star LkHa 233 and its bipolar jet
• Detection of Extended Hot Water in the Outflow from NGC 2071
• Deuterium chemistry of dense gas in the vicinity of low-mass and massive star forming regions
• Spitzer IRS mapping of the central kpc of Centaurus A
• JOYS: The [D/H] abundance derived from protostellar outflows across the Galactic disk measured with JWST
• Gas and Star Formation from HD and Dust Emission in a Strongly Lensed Galaxy
• Mapping the Universe in HD
• The Molecular Hydrogen Explorer H2EX
• GGD 37: An Extreme Protostellar Outflow